National Values Standard
In the UK, only a small number of lines are currently ’ERTMS ready’. ETRMS, or the European Railway Traffic Management System, is an in-cab signalling system providing movement authority information to the driver via an in-cab driver-machine interface. As part of the Digital Railway roll out strategy, more lines are expected to be fitted with ERTMS in the near future, such as the East Coast Main Line and the Trans Pennine route. Each of these lines has unique geographical features and individual operational preferences.
The ERTMS/ETCS National Values are a set of parameters defined by the infrastructure manager to adjust the onboard system behaviour to meet the performance and safety requirements of a defined area or areas of the GB mainline network. The ERTMS/ETCS National Values include parameters for:
- The configuration of ETCS operating mode related ceiling speeds
- The enabling or disabling of ERTMS onboard features
- Or the configuration of operational limits and tolerances.
With the update of the CCS TSI to include baseline 3, additional National Value parameters were introduced that influence the ETCS onboard braking curve calculations. RSSB took the opportunity to review and update its standard on National Values, GERT 8408.
Having reviewed the updated ERTMS Systems Requirement Specification, we undertook a detailed qualitative analysis to determine the changes needed for the standard and guidance. Using expertise from across RSSB, we developed:
- Requirements for infrastructure managers and railway undertakings, setting out a process for how regions can work together to set the values in a way that achieves a balance in safety and performance, while also ensuring interoperability in railway operation.
- Guidance for infrastructure managers’ signalling, performance and safety engineers that provides a common understanding of the safety, performance and drivability aspects of the different National Value parameters, to support decisions on how to determine the optimal parameter values for their regions.
This work on the National Values standard will make it much easier for routes to prepare for the new signalling system, ensuring optimisation of railway operational performance and interoperability.